A sailor from Patuxent River Naval Air Station has been sentenced to 12 years of confinement and a dishonorable discharge, Navy authorities report, at the close of a two-week court-martial following the death of his infant daughter.

Brian Hart, a 23-year-old master-at-arms seaman, also will forfeit all pay and allowances, according to a public affairs director at the Navy Yard in Washington, D.C., where St. Mary’s detectives took part in the military trial that concluded Thursday afternoon with the jurors’ verdict and their decision on the penalty.

Hart will appeal his conviction for murder and the other charges against him, his lawyer said Monday, adding that the defense stands by its position that the child died from a stroke.

At the onset of the trial, before members of the jury were brought into the courtroom and selected, Hart’s lawyer and a prosecutor argued over a doctor’s changed opinion about the head injuries suffered in August 2010 by 4-month-old Brooke Leigh Hart.

Brian Hart faced a maximum sentence of life in prison if convicted of the murder charge, Navy Lt. Cmdr. Rachel Trest, the lead prosecutor, said at the beginning of the proceeding. By that time, the Navy spokesman confirmed, the sailor’s wife, Jessica Hart, had reached a pretrial agreement with the prosecution that was contingent upon her cooperation in the case against her husband. She is scheduled to return to the military court in early December.

Brian Hart earlier was arrested by St. Mary’s detectives and indicted by the county’s grand jurors for second-degree murder in the baby’s death.

St. Mary’s prosecutors said last year in the county’s circuit court that they were dropping their case against Brian Hart because the Navy had requested that the matter be transferred to its authority.

“I would say that the U.S. military did a very good job, and we should be glad that their judicial system is part of our community,” St. Mary’s State’s Attorney Richard D. Fritz (R) said Monday at his office in the county courthouse.

“Twelve years in the federal system means 12 years,” Fritz said.

Detectives alleged in 2010 that Brooke Hart suffered head injuries and fractured ribs during multiple incidents before she died.

She was born prematurely in late March of that year, the county investigators reported, and she remained at a Baltimore hospital’s neonatal intensive care unit for more than three months before she was released to her parents at their home in the Glenn Forest housing area of Patuxent River Naval Air Station. The child was taken to St. Mary’s Hospital in early August of that year, court papers state, and she was transferred to a Washington, D.C., hospital, where she died five days later.

An autopsy on the baby’s body found seven rib fractures on her left side, three rib fractures on her right side and head injuries including a subdural hematoma, according to a statement of probable cause filed in St. Mary’s District Court by Cpl. William Raddatz of the St. Mary’s Bureau of Criminal Investigations. The detective wrote in charging papers that Brian Hart admitted picking the baby up “with great force” and shaking her to get her to go to sleep, and in a separate incident, again picking her up forcefully, allowing her head to snap back.

Robert Bonsib, Hart’s lawyer, said of his client’s conviction and sentence, “Hopefully, there will be some relief through the military appellate process.”

“We’re obviously disappointed at the outcome. We believe that Seaman Hart did not cause the death of his child,” Bonsib added. “We believe it was from a stroke. It was a naturally occurring event.”